Malignant granular cell tumour: a case report and re-evaluation of adverse prognostic features

Granular cell tumours (GCT) mostly follow a benign course. The malignant cases account for 1%-2% of all GCTs with most cases reported in African-American females. It is found in soft tissue of the thigh, rather than the head and neck area for benign lesions. In 1998, Fanburg-Smith et al. proposed six histologic criteria for selection of benign, atypical and malignant cases in the study of 73 GCT cases. However, the reproducibility of some of their criteria is questionable and malignant granular cell tumour still remains a grey zone and lack clear diagnostic criteria. We hereby report a granular cell tumour in an elderly female which morphologically did not fulfill criteria of malignant GCT by Fanburg-Smith et al. but behaved in an aggressive fashion with repeated recurrences and metastases. The need for a simple and practical diagnostic approach is emphasized.